In many conventional lighting systems, phase-cut dimmers have been implemented to dim light sources. Generally, phase-cut dimmers cut a portion of each half-cycle of the waveform of an alternating current (AC) signal, which is typically of 50 Hz or 60 Hz line frequency, thereby lowering the effective voltage delivered to the downstream light source, lowering the intensity of its output. Phase-cut dimmers typically modify the sinusoidal waveform of an AC signal at either its leading edge or its trailing edge. Forward or leading-edge phase-cut control may be provided, for example, by a triode for alternating current (TRIAC) device. Reverse or trailing-edge phase-cut control may be found, for example, in an electronic low-voltage (ELV) dimmer device. In either case, the electric power to the light-emitting device connected to the dimmer is reduced, and its light output can be dimmed accordingly. Pulse-width modulation (PWM) dimming is an alternative approach to providing dimming control and is of a higher frequency than traditional line-frequency phase-cut dimming, making it especially suitable for solid-state lighting technologies. Typically, PWM dimming of solid-state devices is coordinated by an internal processing element.
These and other features of the present embodiments will be understood better by reading the following detailed description, taken together with the figures herein described. The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing.